Study On GPS Weak Signal Processing Using Nonlinear Filter

Traditional GPS receivers can perform high precision in positioning if they can"see"enough satellites in the open sky. But under bad conditions, GPS signals are too weak to be received. High-sensitivity GPS positioning under any conditions is the problem that should be addressed at present.A new structure of GPS receiver for weak signal processing was proposed in this paper. The emphasis was placed on signal acquisition and tracking. For the weak signal acquisition, blocking acquisition was used instead of the traditional methods—serial search and FFT search; For the weak signal tracking, we proposed the nonlinear filter algorithm instead of the discriminations used by standard PLL and DLL, it aimed to get code phase lock and carrier phase lock even in very weak signal.Firstly, the paper described the definition of GPS and its principles, and the definition of weak GPS signals and how they are generated. The key phases of signal processing are acquisition and tracking. So, there was a detailed introduction to both acquisition and tracking by the traditional...